1. Field of the Invention
The present invention relates to duplexer modules and, more particularly, to a duplexer module preferably for use in transmission and reception of signals in at least two communication systems using different frequency bands.
2. Description of the Related Art
In recent years, an increase in the number of frequency bands and support of multiple communication systems have been advanced in mobile phone services in order to address, for example, an increase in the number of subscribers, global roaming enabling services to be used all over the world, an improvement in communication quality, and an increase in the capacity of a variety of content. As a result, multiple duplexers used in radio-frequency (RF) circuits are increasingly installed in mobile phones. In other words, duplexers corresponding to multiple bands and communication systems that are used are increasingly installed in the mobile phones.
In addition to the increase in the number of duplexers installed in the mobile phones, duplexer modules in which multiple duplexers are integrated have been developed in order to decrease the size of mobile phones. Various duplexer modules have been proposed.
For example, Japanese Unexamined Patent Application Publication No. 2003-517239 discloses a duplexer module M1 schematically illustrated in FIG. 16. The duplexer module M1 is connected between an antenna A and a low noise amplifier LNA and a power amplifier PA via switches S, S′, and S″ and includes multiple transmission filters and reception filters. The duplexer module M1 includes transmission filters FT1 and FT2 and reception filters FR1 and FR2, instead of providing a plurality of duplexers each including a transmission filter and a reception filter on a wiring board. The transmission filters FT1 and FT2 are collectively provided at one side of the wiring board of duplexer module M1, and the reception filters FR1 and FR2 are collectively provided at the opposite side of the wiring board of the duplexer module M1. Such an arrangement allows the wiring pattern on the wiring board to be simplified in order to reduce the size of the duplexer module M1.
Technologies to arrange the wiring patterns of multiple surface acoustic wave filters together for simplification are known. For example, Japanese Unexamined Patent Application Publication No. 2002-208832 discloses an elastic wave apparatus schematically illustrated in FIG. 17. In the elastic wave apparatus in FIG. 17, balanced terminals 1305 and 1306 are commonly used for two balance filters 1301 and 1302 having different pass bands. Since an unbalanced terminal 1304 is also commonly used for the balance filters 1301 and 1302 in FIG. 17, the balance filters 1301 and 1302 function as one filter having the two pass bands. However, the elastic wave apparatus may be configured so that the unbalanced terminal is not commonly used for the balance filters 1301 and 1302.
In a typical duplexer module in the related art, multiple duplexers are provided on a wiring board and multiple transmission terminals and multiple reception terminals are collectively arranged on the rear surface of the wiring board. In order to simplify the wiring pattern on a circuit board on which components including the duplexer module, amplifiers, and switches are provided, it is necessary to use a layout in which the transmission terminals of the duplexer module are adjacently arranged and the reception terminals thereof are adjacently arranged.
However, when the transmission terminals of the duplexer module are adjacently arranged and the reception terminals thereof are adjacently arranged in a configuration in which multiple duplexers are provided on the wiring board, the wiring pattern on the wiring board including the duplexers provided thereon is lengthened and complicated, which degrades isolation characteristics and insertion loss.
Although the transmission filter FT1 and the reception filter FR1 support one frequency band and the transmission filter FT2 and the reception filter FR2 support another frequency band in Japanese Unexamined Patent Application Publication No. 2003-517239, the transmission filter FT1 and the reception filter FR1 may support the transmission band and the reception band of one communication system and the transmission filter FT2 and the reception filter FR2 may support the transmission band and the reception band of another communication system. Preparing the transmission filters and the reception filters of at least two communication systems using different frequency bands using the configuration described above to collectively arrange the transmission filters on the wiring board and collectively arrange the reception filters on the wiring board causes the wiring pattern on the wiring board to be lengthened and complicated, thus degrading electrical characteristics.
The technology disclosed in Japanese Unexamined Patent Application Publication No. 2002-208832, was originally intended to commonly use the balanced terminals (output terminals) in the multiple surface acoustic wave filters in the elastic wave apparatus. The idea of arranging the wiring patterns of the duplexer module together in order to simplify the wiring patterns on the circuit board on which the duplexer module is provided is unknown. In addition, a specific method of producing a wiring board that does not have the degradation in isolation characteristics and insertion loss by arranging the wiring patterns together for simplification is not publicly known.